Gold trading

So I'm 100% confused I have been doing stock trading for a little while I been studying everyday. I understand reading charts. And how the news plays a part of certain stocks I been doing options to make money. And slowly investing into ai cryptos and stocks I see tons of trades for gold and they are making a killing on whether the money is going up or down. I don't understand what platform do they use And are they doing futures? Cause I can't find gold on Robinhood or ibkr or tasty trade unless it's in the future side of the platforms. Are they doing futures and how do they set it up to make money from the price going down? Much appreciated if I can get some help